Membrane roofs are roofs that are covered with a polymeric sheet or membrane. These polymeric sheets can be, for example, polyvinyl chloride (PVC), thermoplastic olefin (TPO), or ethylene propylene diene monomer rubber (EPDM), as well as many others. The polymeric sheet is positioned over a roof surface and held in place by fasteners, adhesive, or ballast. Adjacent sheets are bonded together along lap seams to form a unitary single sheet of the polymer covering the entire roof.
Generally, the roofing membrane is either white or black. Theoretically, the membranes could be basically any color.
One chooses a white membrane roof for either aesthetic purposes or to reduce energy costs by reflecting thermal energy. In either event, it is important that the white membrane roof sheeting be clean, i.e., white, subsequent to installation or it will not provide the aesthetic appearance desired nor have the same reflective properties.
Particularly, when replacing an existing roof, it is difficult to keep the new sheeting clean. In a re-roofing application, a section of the old roof covering is removed and new roof membrane is immediately installed in its place. This allows the roof to be fully covered each night. As subsequent sections of the old roof are removed, the roofers walk on the previously installed new membrane. This can scratch and mar the new membrane. Even when installing a new roof, it is difficult to keep the white membrane clean during installation.